Method of cleaning metal articles.



UNITED STATES PATEN T OFFICE.

CHARLES BURROWS MOREY AND CHARLES JOSEPH HUBER, F BUFFALO, NEW YORK,

' ASSIGNORS T0 LARKIN 00., OF BUFFALO, NEW YORK.

METHOD OF CLEANING METAL ARTICLES.

No Drawing.

To all whom it may "concern:

Be it known that we, CHARLES BURROWS MoREY and CHARLES JOSEPH HUBER,citizens of the United States, residing at Buffalo, in the county ofErie and State of New York, have invented a new and useful Improvementin Methods of Cleaning Metal Articles,

of which the following is a specification.

This invention relates to methods of cleaning metal articles byimmersing the same in an electrolyte in contact with a metal of moreelectro-positive properties than the metal to be cleaned.

In methods of this kind as heretofore employed it has been found thatmetal articles can only be successfully cleaned when theelectro-positive metal is clean so that a good contact can be obtainedbetween the articles to be cleaned and the electro-positive metal. Theelectro-positive metal, however, quickly becomes coated when immersed inelectrolytes heretofore used so that in some cases I it has been foundnecessary to employ a third metal for keeping clean the metal with whichthe article is to be cleaned is placed in contact.

The object of this invention is to provide an improved process of thiskind in which the electrolyte itself keepsthe electro-positive metalclean.

In carrying out this process any metal may be employed which iselectro-positive with regard to the articles to be cleaned, zinc beingpreferably employed when silver or gold articles are to be cleaned. Theelectropositive metal may be of any suitable form, a disk or plate beingpreferably employed which may be immersed in the electrolyte whichshould be contained in any suitable vessel or receptacle, preferablymade of nonconducting material. 7

The electrolyte used in this process preferably consists of water inwhich is dissolved a suflicient quantity of some suitable salt to renderthe water a good conductor of 'electricity, about 3 per cent. of commonsalt or sodium chlorid having been found very satisfactory. Other saltsmay, however, be used if desired. A small amount of acid is then addedto the electrolyte, approximately one-tenth of one per cent. (0.1%)having been found to roduce satisfactory results. This acid may e of anysuitable kind such as sulfuric, hydrochloric, acetic, or other acidwhich will not attack the articles to be Specification of LettersPatent.

Application filed June 23,

Patented July 30, 1913'. 1917. Serial No. 176,601.

cleaned. This acid has the property of keeping the electro-positivemetal clean by preventing the formation of a crust of salt or' other,deposit on the electro-positive metal. An electrolyte producing verysatisfactory results can be made by dissolving one-half cup of salt inone gallon of hot water and adding thereto one-third cup of vinegar. Thewater should be as hot as the hands can readily bear.

The electrolyte thus formed is placed into a receptacle and theelectro-positive body is placed on the bottom of the receptacle. Thearticles to be cleaned are then placed into the receptacle in contactwith the electropositive body, whereupon almost instantly after makingcontact they become clean. When the tarnish has been removed from thearticles, they are removed from the electrolyte, rinsed, and if desired,polished with a chamois or flannel cloth.

The action which usually occurs in electrochemical processes of thiskind appears to us that, when placed in the electrolyte, a difference ofpotential exists between the more electro-positive metal and the metalto be cleaned. WVhen' the metal to be cleaned and the moreelectro-positive one are brought into electrical contact, a circuit isestablished and an electrical current flows through the electrolyte fromthe more electro-positiVe metal to the metal to be cleaned, and with theflow of the electrical current nascent hydrogen forms on the surface ofthe metal to be cleaned. This highly active substance reconverts thetarnish and other metallic compounds to the simple metallic substancefrom which they were formed. It is therefore absolutely necessary that agood electrical contact be formed between the artlcles to be cleaned andthe more electro-positive metal, otherwise no current will flow and nonascent hydrogen be produced.

By means of the method described 'the zinc or other electro-positivemetal is kept clean by' the action of the acid in the electrolyte andgood electrical contact can be easily obtained, so that a large numberof articles can be cleaned without producing any perceptible slowingdown of the process or increase in the time required for cleaning thearticles. The method is much simpler than those requiring the use of twometals in addition to the metal to be cleaned and produces thoroughlysatisfactory results,

In the use of most methods employing an alkaline electrolyte with a zincelectro-positive electrode, a troublesome floeculent precipitate formsinthe electrolyte which makes the solution more or less opaque. This(lifficulty is entirely removed by our acitl method in which thesolution remains clear and the process of cleaning can be readilyobserved.

While common salt or sodium chloricl has been found to he verysatisfactory this process, yet it is not intended to limit the inventionto the use of sodium chloricl in the electrolyte, since any other salthaving the property of rendering the liquid a conductor of electricitymay be used, if clesirecl. V

Vi e claim as our invention:

1. The herein tlescribel method of cleaning metal articles consisting inimmersing the articles in an electrolyte containing an acid and inbringing the articles in contact While in saicl electrolyte with a metalof greater electro-pcsitive character than the articles to be cleaned.

2, The rerein clescr'becl method of cleaning metal articles consistingin immersing the articles in electrolyte consisting of Water, a salt amlan acid, in bringing the articles in contact while in said electrolytewith a metal or greater electro-positive character than the articles tobe cleanecl.

3. The herein described method of cleaning metal articles consisting inimmersing the articles in an electrolyte consisting of Water containingapproximately three per cent. of salt and one tenth of one per cent.

acid, and in bringing the articles in contact While in said electrolytewith a metal or" greater electro-ipositive character than the articlesto he cleanecl.

4, The herein described methocl of clean ing metal articles consistingimmersing the articles in an electrolyte containing an acid anclbringing the articles While immersed into contact with a body of zinc.

5. The herein described method of clean ing articles of silver, gold orthe like, con sisting in immersing the articles in an electrolyteconsisting of Water containing salt and vinegar in approximately theproportion of one-half cup of salt ancl one-third cup of vinegar to agallon of Water, immersing the articles in the electrolyte and bringingthe same While immersed into contact with a hotly of zinc.

6. The herein described method of cleaning articles of silver, gold orthe like con sisting in immersing the articles a Water solutioncontaining approximately three per cent, soclium chloricl and one-tenthof one per cent, acetic acicl, in bringing the articles While saiclsolution into contact With piece of zinc also immersed in the solution,in removing the articles from the solutiom in rinsing them and inpolishing them.

I. The herein clescribecl methotl of clean ing metal articles consistingin immersing the articles in a hot solution consisting of salt andvinegar dissolved in Water, and in bringin the articles While in saidsolution into contact with a metal of greater electro positive characterthan the articles to be cleaned,

Vgitness our hands this 21st day of June, 191' CHARLES BURBGWS @SEPH HUBR.

Witnesses:

Wrnnnn L. linker,

